Airdate: Feb 14, 2001
Scientist: Persis Drell
What is the smallest unit of matter making up our world? Thanks to particle physics, the answer to that question keeps getting smaller and smaller.
What's our world made of? What's the smallest unit of matter? These are questions people have been investigating for a long time. Thanks to the field of particle physics, the answers to these questions have been getting smaller and smaller. I'm Jim Metzner, and this is the Pulse of the Planet.
"We want to know what is the smallest building block out of which all matter is made. What are the interactions that hold those building blocks together?"
Persis Drell is a particle physicist at Cornell University.
"I have a nine-year-old son who likes Legos. If you play with Lego's, there's a smallest unit that all other Legos are made from. We're trying to find the smallest building block, out of which all matter is made."
"Now people used to think that the world was made of atoms. Experiments probed the atom and found it had a structure. It was a small nucleus, surrounded by a cloud of electrons. As further experiments in the 20th century probed the nucleus, they found that it was also a composite object, made of protons and neutrons. As yet further experiments probed protons and neutrons, they were found to be made of smaller fractionally charged particles called quarks. To date, we believe that electron-like objects and the quarks are the fundamental building blocks of matter."
In addition to searching for the smallest units of matter, scientists have identified certain fundamental forces such as gravity which hold matter together.
"The field of particle physics is trying to understand those fundamental forces and fundamental particles. Are there yet smaller building blocks? Are there more forces? Those are the questions of particle physics."
Pulse of the Planet is presented by the National Science Foundation. I'm Jim Metzner.